Adding antifreeze to heating system

Neilw

Hi all,

Are there any downsides to adding an antifreeze to a heating system?
I would like to reduce the chance of burst pipes if we get a bad winter again if the house is left with the heating off.

I found some recommendations for fernox alphi-11. http://www.fernox.com/files/Fernox/Content/PDF/English/Alphi%2011%205L.pdf
Second question, how do you get the antifreeze into the heating circuit, should the system be drained first?

Thanks,
Neil.

Billy Bunting

Alphi 11 is good stuff use it quite a bit in holiday homes it's also an inhibitor so is a great addition to any system.
You need to drain the system enough so the chemical is in the system and not just sat in the expansion tank, but it would probably be advisable to drain the system completly and flush it a few times to be sure it's clean.

Neilw

Billy Bunting wrote: »

Alphi 11 is good stuff use it quite a bit in holiday homes it's also an inhibitor so is a great addition to any system.
You need to drain the system enough so the chemical is in the system and not just sat in the expansion tank, but it would probably be advisable to drain the system completly and flush it a few times to be sure it's clean.

Thanks, any idea roughly how much a plumber would charge to do the job?

Billy Bunting

At a guess and dependent on the flush €150/200 including the Alphi 11.

Sparkpea

I'm glad this topic has rose because I need some myself for a few farms I do. Currently changed 4 burst rads in an open farm coffee shop that pinholed in the winter, another 5 I think to do in an another outbuilding before the winter. I've been asked to put antifreeze in once the boiler is repaired (burst also).

From fernox website and the link above I cannot see how much I would need to add. Is there a rule of thumb like 5L per 10 rad's or anything (obviously depending on size of rads and run of pipework). It doesn't say how many litres of a system that 5L should support or else I can't see it.

Any advice then on quantity to add etc.

Billy Bunting

There is a booklet that comes with the product but from memory i think it's dependent on system size the quantity required to protect down to a curtain temperature.

Sparkpea

The word from Fernox rep is that 25% of the system needs to be antifreeze. They work off the rule of thumb that 10 rads is approx 100litres. So for a 10 rad system you would need to add 25L of antifreeze to achieve -11 protection, 30L for -15 etc. (as per link in OP).

Prices I've got today are approx £30 all in for 5L and £130 all in for 25L.

Pricey enough I guess but not if you consider the cost of burst pipes.

Neilw

Billy Bunting wrote: »

At a guess and dependent on the flush €150/200 including the Alphi 11.

Thanks, can you recommend a plumber to do the job? I'm in celbridge / leixlip area.

Hootie

Just wondering how do you actually get the antifreeze into the system if you have a pressurized system?

Sparkpea

Hootie wrote: »

Just wondering how do you actually get the antifreeze into the system if you have a pressurized system?

you drain a bit off, either at boiler or radiator etc. then add it to the system, highest point is probably easiest through a tundish or use a fernox injector to inject it through a radiator airvent.

Hootie

I was talking about this to lads in work and he mentioned the best way is in a towel rad as they have a blank off on the top. This is the easier option for me as I have a pressurized system and there is no where in the boiler house to add the antifreeze

heinbloed

As Sparkpea said: drain the system and ad your fluid. Then top it up with water until the desired pressure is achieved.

The boiler house won't allow you to influence the pressurised system. You have to 'open' the pressurised system itself, the door to the boiler house won't do.
(

I was talking about this to lads in work and he mentioned the best way is in a towel rad as they have a blank off on the top. This is the easier option for me as I have a pressurized system and there is no where in the boiler house to add the antifreeze

)

Calculate the ratio of water-antifreeze liquid as well. Don't overdoe it, don't underdoe it. The necessary concentrations are written on the bottle/user manual.

Get a plumber in if there are difficulties in understanding this advice.

Billy Bunting

or maybe you could ask Heinbloed to pop in and do it for you, with the manual obviously. :rolleyes:

Sparkpea

glad I put info on here to save me ringing around places again! bumped it up

heinbloed

Adding anti-freeze to a water based systems changes it's thermal properties.
Not only that 'dilluted water' carries less thermal energy, the mixture's thermal transmission is decremented.
Meaning a heat exchanger'surface (here: radiators) will have to be three times as large compared to a water filled system.
So with the proposed action of the OP(adding antifreeze to a water based CH system) the radiators have be larger and/or the flow temperature and flow rate has to be increased.

We see frequently questions here in the forum where people ask if they can connect a 2-loop standard cylinder designed for water(2 heat exchangers ) to a ST system.
The energetic performance of such non-calculated systems will be poor if the ST side (it's thermal carrier)uses anti-freeze.
Always make sure that the thermodynamic conditions all the elements involved are suitable for the planned outlay.